Abstract
The extraction optimization of the poplar-type propolis was performed in order to improve the isolation of flavonoids as well as the corresponding antimicrobial activity of the products obtained. The efficiency of flavonoids extraction depended upon the type of extraction media used, following the rank 80% ethanol >40 ethanol>> water, regardless of pH value. Ultrasound assisted extraction was as efficient as the maceration procedure, offering additional benefits such as short duration time and low extraction temperature. The antimicrobial efficiency of extracts prepared with 80 and 40% ethanol against the tested microbial stains was comparable, regardless of the extraction technique used, while aqueous extracts mainly showed scarce activity. Observed activity against the yeast Candida albicans strongly correlated with flavones and flavonols content in extracts prepared (r2=0.8217), while regression analysis showed that beside flavonoids, some other components which were successfully extracted from the crude propolis contributed to the observed antimicrobial efficiency against Bacillus subtilis and Staphylococcus aureus.